Blaine T. Bettinger, Ph.D., J.D., “Visual Phasing: Mapping DNA to Your Grandparents”

“Visual Phasing: Mapping DNA to Your Grandparents”

Blaine T. Bettinger, Ph.D., J.D.




Visual Phasing is one of the hottest new tools in genealogy. It allows you to map the DNA of two or more siblings to the four grandparents, WITHOUT having tested either the parents or grandparents. As we’ll see, with enough siblings, it allows you to recreate almost the entire genomes of your four grandparents. You’ll also be able to quickly determine which of the four grandparents’ lines each of your matches share!

To perform visual phasing, you need DNA (transferred to GEDmatch) from three or more siblings (although we will talk about some tricks for just two siblings). Preferably you’ll also need good cousin matches on at least some of the grandparents’ lines. Armed with just this, you’ll be able to visually phase the DNA!

Bettinger_B (3)Blaine Bettinger, Ph.D., J.D., is an intellectual property attorney by day and a genetic genealogist by night. In 2007 he started The Genetic Genealogist (, one of the earliest blogs on the topic. For the past eight years, it has been his mission to bridge the gap between traditional genealogy and genetic genealogy. He has been interviewed and quoted on personal genomics topics in NewsweekNew Scientist, Wired, and others. He authored I Have the Results of My Genetic Genealogy Test, Now What? in 2008, which is distributed by Family Tree DNA to all of their new customers. An update to the ebook is in the works.

Blaine frequently authors articles and gives presentations to educate others about the use of DNA to explore their ancestry. He is an instructor for genetic genealogy courses at the Genealogical Research Institute of Pittsburgh (GRIP), Salt Lake Institute of Genealogy (SLIG), Virtual Institute of Genealogical Research, and Family Tree University. Blaine was also recently elected to the New York Genealogical and Biographical Society’s Board of Trustees.

Course Schedule

Day One

  • Session One: “Visual Phasing: An Introduction”: In this introduction, we will learn all about recombination and the fundamental basics of Visual Phasing. We will also begin to set up a workspace for performing Visual Phasing.
  • Session Two: “Visual Phasing: Finding Recombination Points and Assigning Segments”: Identifying recombination points among the siblings, and assigning segments to them, is the most challenging aspect of visual phasing, but we will tackle this with ease!

Day Two

  • Session Three: “Visual Phasing: Using Cousin Matches to Map Assigned Segments”: Now that we have assigned segments, we can determine who those segments came from. Cousin matches help us do just that!
  • Session Four: “Visual Phasing: Using the Phased Segments in Your Research”: What do we do with the phased segments once we have them? Among other things, we can map our own chromosomes, identify which of our four grandparents a match maps to, recreate our grandparent’s genomes, and much, much more!